Massive reorganizations of zinc have been implicated in the regulation of a variety of human physiologic activities. Recently, it was discovered that intracellular and extracellular zinc fluxes are vital to successful mammalian oocyte development and occur both pre- and post-fertilization. However, there is little understanding of the molecular mechanisms behind the zinc-dependent switching events that dictate oocyte maturation. Without this knowledge, the biomedical community lacks the ability to assess what makes a good egg and develop potential reproductive therapies. Therefore, the goal of this proposal is to elucidate the cellular needs for zinc by tracking its accumulation and localization during oocyte maturation. I hypothesize that variation in intracellular zinc content during maturation drives cell cycle progression by fulfilling the metal requirement of key Zn-proteins in the maturation process. These proteins include vital Zn-containing enzymes needed to catalyze certain cellular processes as well as zinc-receptor proteins where the presence or absence of their metal cofactor serves as a regulatory switch. This hypothesis will be addressed by employing radioactive zinc tracers to track and quantify Zn2+ accumulation and redistribution. In addition, these studies will elucidate the physiological significance of the efflux event at fertilization known as the zinc spark. Lastly, changes in zinc metalloproteome will be characterized using radioactive zinc tracers in conjunction with native electrophoresis to reveal which Zn-proteins are activated during oocyte maturation. The data obtained from this study will serve as a framework for establishing a novel Zn-dependent mechanism that dictates cell cycle progression in the oocyte, thus providing new means for assessing oocyte health. Insights gained from this research project will be applicable to other zinc-dependent physiologies as well. This award will support a broad array of multi-disciplinary training activities and experienc with the goal of providing robust preparation for a tenure-track position in a Research I university. Training activities will increase key competencies in the areas of scientific communication, mentoring, lab management, in addition to broadening technical skills.